Hydraulic damping device cylinder construction



April 1947; G. M. MAGRUM 2,419,651

HYDRAULIC DAMPING DEV ICE CYLINDER CONSTRUCTION Filed Jan. 51, 1944 2 Sheets-Shei 1 ZWVEWZQF N \9 627814485 M XVnaeum Apr 2 1 4 G. M. MAGRUM 2,419,651:

HYDRAULIC DAMPING DEVICE CYLINDER CONSTRUCTION Filed Jan. 31, 1944 2 Sheets-Sheet 2 6159 M465 W7: M4060.

Patented Apr. 29, 1947 HYDRAULIC DAMPING-DEVICE CYLINDER CONSTRUCTION 1 Gervase M."Magrum, Bufialo; N. Y.-, assig nor to T l Houdaille- Hershey Corporation; Detroit; Mich, Y a corporation of Michigan Application January 31, 1944, Serial No. 520,427

. 6 Claims.

"Myinvention' relates to hydraulic damping devicesof the rotary type adaptedflparticularly for functioning. as shock absorbers "on vehicles or as shimmy-dampers for wheels on airplane landing the shoulder I4 and against the 'outerends of-the abutment legs, a clamping waIl 20 threading into the end of the cylinder part II to 'exertpressure against the end wall I 9 to hold it securely against gears. li'the' shoulder Iiandthe abutment legs with" the wherejhydraulicjdevices of the type referred to inner end'wall l seatin against theshbiilder I3. are to beused; particularly in airplane service 'The cylinder pa t Iii is slotted i y wher the" temperature may vary through a Wide tween the shoulders I3 and I4 to'provide'key'ways range-:as-for example, from-160 F. to 65 below i 2'! and 22 for keys 23 and 24'which engage in keyzero;-the devices must be built te'function satisway's 25'and'2ii in' the-abutment legs l-"l and I8 j factorilywithcomparatively light hydraulic fluid so as to hold the abutment structure against*ro "--such"'as 'oil. It. therefore becomes necessary to .tatio-n'in' the'cylinder. "Tapered 'dowel "pinsf 21 -reduceto aminimum:manufacturing'tolerances extend through tapered holes' 28 in the outer" end and "running "clearances; and further to provide wall 59' and are pressed into matching 'tapered sealing means in order: toeliminate leakage. pan holes" 29 at theends of the abutment legs- Hand "*ticularlyinternalleakage. 8 for holding" the abutment legs intimately It is,-"therefore, an-important'object of my inagainst the Wall'of' cylinder part-16. VV-heitthe "vention to provide improved construction ""101 asouter end wall I9 is'presse'd in by the clamping 'sociation ofparts to reduce to a minimr-an' manwa1l"2il, the peripheral engagement "of th'e" wall ufacturing tolerances and runnin clearances; to-- against the shoulder M, in addition toitsrengagew h proved"arra ement of sealing -ment'against the ends' of the'abutment'legs-fiwill means-between internal operating 'parts of the hold thee nd wall against inward deflection under r device to cut down to a minimum internal leakpressure when=the device is in operation; an'dthe ageso that'thedevice may function at maximum abutment legs will be held against the Wall" of efficiency" at all: timesithroughout a wide tem- 'c'ylinder part Ill. ""D re ran e. The piston structure for the'device comprises "The"variousimprovement features of .myinthe-cylindrical hub 3flextending betweenthe vention' are e'mbodiedinthe structure'shown on innerand'outerend Walls I5'and I9; and'theshaft the drawings in which: 3 I" which extends through the bearing opening in Figure I is a longitudinalsection on plane '-the end Wallis and through the clamping'wall Figure i 26. 'At' its outer end the shaft is adapted for con- F ure 2 is a section in plane II'II Figure 1; nection with a lever (not shown) for connec- Figure 3 is a section on plane' III III Figtion with a structure to be controlledJWhile the ure 1; "cylinder C is 1 provided with ears or win gs 32 Figure 1 is an enlarged sectionof one of the whereby it may be secured on asupport. ---zreplenishingyalveassemblies; and I "The piston hub has the vanes -33' and 34 Figure 5 is an inner end view'of a valve cage. thereon "engagin at their outer e'nds againstthe -In the device *shownf-the cylinder C has a cylinder wall lfi and-these vanes together with remiddle 'wall portion Ill and the outer and inner the piston'hub and the abutment legs, dividethe wall portions H1 and: IZJ' Th'e inner wan portion -cy1inder'space between the endwall'slS and I9 IZ isfo'flless inner diameter'than the'middle wall into diametrically opposite hydraulic-' wor'king mpo'rtion I102 totleavethe annular'sshoulder' l3, while chambers" 35; 3.5 and 36, 36. mathe'a outer .po'rtion H is' of larger inner 'diameter At its inner end the piston hub has the bore or --zithan:thezmiddlecpcrtionvto' leave? the annular chamber 3Twhichreceives" the bearingplug 38 IiShOu1dB1"-l|4...-'.ZIII the: inner r endfo'fthe cylinder secured inthe end wall I51 Extending outwardly errpart :lflsi the: inner :end wall I5-which seats "from this'eha'mber through the piston hub and a:againsjizthe:inner:shoulder'I3=and2has a'boss I6 shaft islthe "bore-'39, a valve s'eatplug-" lfl being fitting-into rthe outer end ofi"the'cylinder part interposed; Theseatplug has" the cylindrical villi Integral with? the end :wall I5 are the di- "svalve''l therein whichhas the bor'e l2 connected ybpnosit ab m n less ll and I8 by the'port 43 with the orifice 44 which extends h' 'wa l fit against 511671111131 from the channel "45 surrounding the seat plug. lzfacefo'f the cylinder-part" IlLrThe. abutment legs 1 :In'rthearrangement showmthe valve is-connectratermi-natesatitheir outer'ends'inlthe plane'of the 1 ed by a bi-metalli'c thermostat coil with an iouterlshoulderiI4. *Fitting into the cylinder part 'i'adjusting pin 46 in the plug assembly 41 in" the i 5 I21: iszztheiouteraend wall-:19 whichseats against fifi outer: end of the bore 39 bymeans of'wliich pin the valve M may be set for overlap of its port 43 with the orifice M for the desired resistance to the flow through the valve. Ports 49 extending radially through the piston hub connect the valve plug channel 45 with the hydraulic working chambers 35, 35, while ports 50 connect the chamber 31 with the hydraulic workin chambers 35, 36. Upon oscillation of the piston, the displaced hydraulic fluid will flow from one set of working chambers into the other against the flow resistance caused by the orifice 3 i.

Means are provided for keeping the hydraulic working chambers at all times replenished and filled with hydraulic fluid. Within the cylinder part I2 is a plunger 5| between which and the outer end Wall I5 is the reservoir space 52. The outer end of the cylinder part [2 is closed by a detachable cover 53 between which and the plunger 5! is a spring assembly 54 which tends to shift the plunger inwardly toward the end wall l5, the annular stop boss 55 on the plunger limiting such inward movement. The plunger movement is guided by the stem 56 which projects intothe guide flange 51 extending from the cover 53. A sealing gasket 58 between the plunger and the cylinder wall prevents leakage past the plunger from the chamber 52. A check valve controlled nipple 59 communicates with the chamber 52 and through which hydraulic fluid may be charged under pressure into the chamber for flow therefrom into the working chambers through replenishing valve struc ures V in the end wall l5. After the hydraulic chambers have been filled. the pressure will force the plunger 50 outwardly aga nst the resistance of the springs 54 and then, after closure of the nipple 59, the spring assembly will tend to force the plunger inwardly for flow of the hydraulic fluid from the chamber 52 into the hydraulic chambers to keep them at all times completely filled. A gauge pin 58 extends from the plunger stem outwardly through a passageway 6| in the cover 53. and after the device has been charged with hydraulic fluid and the plunger is shifted outwardly, the end of the gauge pin may be observed through a window 62 in a cap 63 threading into the cover 53. Preferably packing S4 in the cap surrounds the pin. The length of the pin exposed through the window 52 will correspond with the distance the plunger has been shifted outwardly when the device was charged with hydraulic fluid. The pin will then indicate when it is time for recharging of the device.

' Describing now the valve structures V. two of such structures are shown at opposite sides of one of the abutments, such as the abutment I8, for flow of the hydraulic fluid from the reservoir chamber 52 into the hydraulic working chambers 35 and 36 at opposite sides of the abutment. Each valve structure comprises a cup-shaped cage 65 threading into a recess 56 in the inner end wall 55. The cage cooperates with the bottom wall of the recess to provide a. valve chamber 6': connected with the respective hydraulic working chamber through ports 68, the valve chamber being connectable with the reservoir 52 through ports 69 in the bottom wall of the cage. As shown on Figure 2, the ports 68 are at one side of the bottom wall of the recess 66 so as to be close to the abutment I 8. Within the valve chamber is the valve disk 10 for seating against the annular seat ridge ll surrounding the ports 59, the valve disk having the stem 12 surrounded by a spring 13 which abuts the valve disk and the bottom wall of the recess 65 and tends to hold the valve disk seated. The valves will permit flow of hydraulic fluid from the reservoir 52 into the respective working chambers but will prevent reverse flow. A small radial notch 14 is provided in each seat ridge H, these notches permitting escape of air or gas from the working chambers into the reservoir after the valves have been firmly seated by their springs and by the hydraulic pressure in the working chambers. The working chambers are thus kept free of air which might interfere with the efficient operation of the shock absorber. These vent openings it are too restricted to permit any material escape of hydraulic fluid from the working chambers into the reservoir.

The outer side of the outer end wall it and the inner side of the clamping wall 25 are recessed to provide the annular space M. As shown, a passageway 15 extends through the abutment leg I! and the end wall l5 to connect the reservoir space 52 with the hole 29 in which the dowel pin 21 is inserted, this pin having the passageway Hi therethrough. The space 14' is thus at all times in connection with the reservoir [2 and is kept filled with hydraulic fluid so that the fluid pressure against the outer sides of the end walls [5 and i9 is balanced.

To prevent leakage to the exterior of th shock absorber along the piston shaft, 3. suitable packing assembly TI is provided in the recess 18 in the clamping wall 28, this packing assembly being held compressed around and against the shaft by the member 19 under pressure of the spring 80. The escape of hydraulic fluid from the Working chambers out between the cylinder wall and the end wall It is prevented by sealing or packing material 8 I,

The operation of the hydraulic device thus far described is well known in the art. Upon relative rotary movement of the cylinder structure and piston structure, hydraulic fluid is displaced from one set of working chambers into the other, the rate of flow and consequently the shock absorbing or damping power of the device being controlled by the orifice 44. The spring pressed plunger 5! exerts at all times a predetermined pressure against the fluid in the reservoir 52 to keep the working chambers fully replenished and filled by way of the replenishing valve structures V. After a period of heavy service of the hydraulic device, some leakage of hydraulic fluid to the exterior may have occurred, and when the device is to be serviced and the gauge pin 60 indicates that the reservoir 52 is not filled, then the device may be recharged with hydraulic fluid by Way of the check valve nipple 59.

In order that the hydraulic device may function in full efliciency at all times, internal leakage between adjacent high and low pressure hydraulic working chambers must be held down to a minimum. This is accomplished by means of packing strips between various operating parts. Each of the abutment legs I! and I8 has a channel 82 in its inner end extending from the outer end of the legs and terminating close to the end wall l5. As shown, these channels. are of rectangular crosssections and in each channel is inserted a packing strip 83 comprising a body of resilient elastic material provided with a core 84 to which it is bonded. The core may be of metal, or of nonmetallic material to be axially rigid but laterally somewhat flexible. The strip body, besides being resilient and elastic, should be of material which will resist deterioration by the hydraulic fluid and which has suflicient wicking characteristics so as to absorb hydraulic fluid, such as oil, for lubricating the surface engaged by the strip, the strips 83 beingzheldrin: engagement with the .outerrsuriace .fiow between the high and lowpressure hydraulic workingichambers at opposite sides of the abutments' when .the device is in operation. bodies of the strips could be of some form of synthetic :rubber sumciently porous to absorb and hold oil, or the bodies could be of some rubberlike'composition'which would have sufiicientwicking characteristics, 7

Each of the piston'vanes 33 and 34 has inlits outer end a channel 85 extending from one side of the vane to the other, and in these channels sealing strips 36 are inserted for engagement with the inner surface of; the cylinder part ill to prevent leakage between the ends of the vanes and the cylinder wall from the high pressure to low pressure working chambers. Ih vanes at their inner sides are also provided with channels 8'! for sealing strips 88 for sealing engagement with the inner end Wall I5 to prevent leakage between working chambers around the inner sides of the vanes. Channels '89 may also'be provided inlthe outer sides of the vanes to receive sealing strips Bliifoi sealing engagement with the outer end wall 9 to prevent leakage between working chambers The outer end of the piston hubltll has the channel 9| therein'for receiving a sealing ring92 to surround the piston shaft and to have sealing engagement with the outer end wall l9, the channels 89 in the outer :sides of the piston vanes communicating with the annular channel 9! so that the sealing strips 9%! will abut the sealing ring 92. The sealing ring will cooperate with the sealing strips 99' to prevent leakage between working chambers, and the sealing ring will prevent leakage from the working chambers out between the shaft and the end wall it.

At its inner end the piston hub is shown provided with an annular channel 93 for the sealing ring 94 for sealin engagement with the inner end wall I5 to prevent leakage between working chambers. Thus, with the sealing means interposed between the relatively moving and operating parts of the hydraulic device, internal leakage between adjacent hydraulic working chambers is reduced to a minimum. As the outer ends of the abutment legs are intimately engaged by the end wall l9 under pressure of the clamping wall 26, there can be no leakage between working chambers past the outer ends of the legs and therefore no sealing means are necessary between the legs,

and the end wall.

It will, of course, be understood that various details of construction may be varied through a wide range without departing from the principles of this invention and it is, therefore, not the purpose to limit the patent granted hereon otherwise than necessitated by the scope of the appended claims.

I claim as my invention:

1. In a hydraulic device of the type disclosed, a cylinder wall having an inner annular internal shoulder and an outer internal annular shoulder, an inner end wall seating against said inner shoulder and having abutment legs extending outwardly therefrom with their outer ends terminating in the plane of said outer annular shoulder, an outer end Wall within the outer end of said cylinder seating against said outer shoulder and the outer ends of said abutment legs, and a clamping member threadin into the outer end of the cylinder wall to exert pressure against said outer end wall to hold said end wall intimately against said outer shoulder and outer ends of the The abutment; legs and with" said: inner r-wall securely seated against said inner shoulder.

, 2. In a hydraulic device of the type disclosed, a cylinder "wall having an inner annular internal shoulder and-an outer internal annular shoulder,

aninner end wall seating against said inner shoulder and having abutment legs extending outwardly therefrom with their outer ends terminating in the plane of said outer annular shoulder, an outer end'wallwi'thin the outer end of said cylinder seating against said outer shoulder and the outer ends of said abutment legs, a clamping member threading into the outer end'of the cylinder Wall to exert pressure againstsaid outer end wall to hold said end'wall intimately against said outer shoulder and outer ends of the abutment legs and with said inner wall securelyseated against said inner shoulder, said outer end wall having tapered openings therethrough and said abutment legs having tapering openings at their outer ends forming continuations of the tapering openings through said outer end wall, and tapered pins driven into said aligned tapering openings for holding said abutment legs intimately against the inner face of said cylinder wall.

3, In a hydraulic device of the type disclosed,

a cylinder wall having an intermediate annular internal shoulder and a second shoulder disposed adjacent to one end of the cylinder wall spaced from said intermediate shoulder, a wall member seating against said intermediate shoulder and having abutment legs extending outwardly therefromwith their outer ends terminating-in the plane ofsaid outer annular shoulder, a wall member seating against said second shoulder and the outer ends of said abutment legs, aclamping member secured to the end portion of the cylinder outwardly beyond said second shoulder to exert pressure against said wall member to hold the latter intimately against said second shoulder and the outer endsof the abutment-legs'and thereby holding said inner Wall member securely seated against said intermediate shoulder, said cylinder wall extending axially beyond said inner wall member oppositely to said abutment legs to provide a hydraulic chamber, and means closing the end of the cylinder extension.

4. In a hydraulic device of the type disclosed, a cylinder wall having an intermediate annular internal shoulder and a second shoulder disposed adjacent to one end of the cylinder wall spaced from said intermediate shoulder, a wall member seating against said intermediate shoulder and having abutment legs extending outwardly therefrom with their outer ends terminating in the plane of said outer annular shoulder, a wall member seating against said second shoulder and the outer ends of said abutment legs, a clamping member secured to the end portion of the cylinder outwardly beyond said second shoulder to exert pressure against said wall member to hold the latter intimately against said second shoulder and the outer ends of the abutment legs and thereby holdin said inner wall member securely seated against said intermediate shoulder, said cylinder Wall extending axially beyond said inner wall member oppositely to said abutment legs to provide a hydraulic chamber, and means closing the end of the cylinder extension, said outer end member and said clamping member bein constructed and arranged to provide a hydraulic chamber therebetween, one of said abutment legs having a passageway therethrough communicating with both of said chambers.

5. In a hydraulic device of the type disclosed,

a cylinder wall having an intermediate annular internal shoulder and a second shoulder disposed adjacent to one end of the cylinder wall spaced from said intermediate shoulder, a wall member seating against said intermediate shoulder and having abutment legs extending outwardly therefrom with their outer ends terminating in the plane of said outer annular shoulder, a wall member seating against said second shoulder and the outer ends of said abutment legs, a clamping member secured to the end portion of the cylinder outwardly beyond said second shoulder to exert pressure against said wall member to hold the latter intimately against said second shoulder and the outer ends of the abutment legs and thereby holding said inner wall member securely seated against said intermediate shoulder, said cylinder wall extending axially beyond said inner wall member oppositely to said abutment legs to provide a hydraulic chamber, and means closing the end of the cylinder extension, said outer end member and said clamping member being constructed and arranged to provide a hydraulic chamber therebetween, one of said abutment legs having a passage therethrough communicating with both of said chambers, said passage having a pin therein connecting said outer wall member and said abutment leg against relative rotation, said pin having a passageway therethrough for uninterrupted communication between said chambers through said passage.

6. In a hydraulic device of the type disclosed, a cylinder wall having an intermediate annular internal shoulder and a second shoulder disposed adjacent to one end of the cylinder wall spaced from said intermediate shoulder, a wall member seating against said intermediate shoulder and having abutment legs extending outwardly therefrom with their outer ends terminating in the plane of said outer annular shoulder, a wall member seating against said second shoulder and the outer ends of said abutment legs, a clamping member secured to the end portion of the cylinder outwardly beyond said second shoulder to exert pressure against said wall member to hold the latter intimately against said second shoulder and the outer ends of the abutment legs and thereby holding said inner wall member ecurely seated against said intermediate shoulder, said cylinder wall extending axially beyond said inner wall member oppositely to' said abutment legs to provide a hydraulic chamber, means closing the end of the cylinder extension, said outer end member and said clamping member being constructed and arranged to provide a hydraulic chamber there- 'between, one of said abutment legs having a passageway therethrough communicating with both of said chambers, and means afiording communication between the chamber on the extension side'of'said inner wall member and on the opposite side of the inner wall member and including one-way valve structure.

GERVASE M. MAGRUM.

REFERENCES CITED The following references are of record in the file of this patent: 

